My building is on an old chiller system, so my AC is off ~5 months out of the year. My windows are open the entire time, and I usually have fans set up too to try and keep things cool.
When my AC is on, absolutely never. It is hot here like 7 months out of the year.
This seems like a nothing burger. Plenty of things you shouldn’t ingest like BPA, plastic, and solder are perfectly benign when used to construct consumer electronics.
I’d be more interested to hear they found something that leeches through the skin being used to create the body of the headphones.
Honestly I think its been years. There’s some hard water on the lid, but no traces of mold or anything like that. It also tastes and smells normal to me.